Heretofore, there has been proposed an electrochemical capacitor that allows to generate electrochemical capacitance by depositing titanium oxide and the like on surfaces of activated carbon fibers (refer to Patent literature 1).
Moreover, there has been proposed an electrochemical capacitor that allows to generate the electrochemical capacitance by forming amorphous oxide whiskers (refer to Patent literature 2).
Furthermore, there has been proposed a lithium-ion secondary battery using, as an electrode, a substrate on which tungsten oxide whiskers and the like are formed (refer to Patent literature 3).